This invention is related in general to the field of telecommunications equipment. More particularly, the invention is related to system and method of preserving stable calls during a split mode operation of telecommunications equipment.
Telecommunications equipment are often constructed with redundancy so that failures do not produce catastrophic outages. These systems often have at least two identical and redundant planes. The redundant planes typically operate in an active-inactive mode. In active-inactive mode, the first plane is actively carrying telephone call traffic and the second plane is placed in a hot standby mode. In the hot standby mode, the second plane also carries live traffic but its operations are ignored. If the first plane fails or performs in a faulty manner for any reason, the second plane may be immediately switched from hot standby to active.
In 1996, DSC Communications Corporation (now Alcatel USA) of Plano, Tex., began using a split mode process to perform system hardware and/or software upgrade or maintenance to shorten the time the system is taken entirely off-line. Briefly, the split mode process splits the redundant system into two simplex systems, one becoming the active side and the second becoming the inactive side. During split mode, the active side carries the load of the entire system while the inactive side gets upgraded with new hardware and/or software. When such upgrade has been done, it is made the new active side and begins to carry call traffic. The old side becomes inactive. The old side is then combined into the new side so that both are running the new software load after the new side has been shown to operate satisfactorily. The combined sides then return to the previous operating mode, where one side is active and one is in hot standby. In this manner, system outage is significantly minimized.
Although split mode operation advantageously causes less call disruption because of shorted system down time, stable calls still become disconnected when the two sides swap the active-inactive operating status. In other words, the stable calls being handled by the active side at the time the active side becomes inactive and the inactive side becomes active are disconnected. This result is especially distressful when stable emergency calls are unwittingly disconnected.
Accordingly, there is a need for a system and method of preserving stable calls during product upgrade via a split mode operation for telecommunications equipment. In one aspect of the invention, a computerized method of preserving stable calls during a split mode operation of telecommunications equipment includes the steps of sending a call block update message, for each call block in the call block file, from a first side of the telecommunications equipment to a second side of the telecommunications equipment. The call block update message includes dynamic call state data on the stable call handled by the first side and stored in a call block in the first side of the telecommunications equipment. The method includes sending a call block update acknowledgement message from the second side of the telecommunications equipment to the first side of the telecommunications equipment in response to receiving the call block update message. The above steps are repeated until all dynamic call state data in the call block file is duplicated and sent to the second side.
In another aspect of the invention, a computerized method of preserving stable calls during a split mode operation of telecommunications equipment includes the steps of scanning a first call block file having dynamic call state data associated with the stable calls being processed by an active side of the telecommunications equipment, populating and sending call block update message with the dynamic call state data of the stable calls to an inactive side of the telecommunications equipment, sending call block update acknowledgement messages from the inactive side of the telecommunications equipment to the active side of the telecommunications equipment in response to receiving the call block update messages, and storing the dynamic call state data in the received call block update messages in a second call block file of the inactive side of the telecommunications equipment. The above steps are repeated until all dynamic call state data in the first call block file is duplicated in the second call block file.
In yet another aspect of the invention, telecommunications equipment is operable to execute a computerized method of preserving stable calls during a split mode operation of telecommunications equipment. The computerized method includes the steps of sending a call block update message from an active side of the telecommunications equipment to an inactive side of the telecommunications equipment, sending a call block update acknowledgement message from the inactive side of the telecommunications equipment to the active side of the telecommunications equipment in response to the call block update message, and repeating the above steps until all dynamic call state data in the call block file is duplicated and sent to the inactive side.